How likely is it for a rotor to lose magnetic strength? I have a '78 GL1000 with charging issues and am troubleshooting. I know a sharp blow to the rotor can cause problems (like dropping it repeatedly on a cement floor) or heating it until is is cherry red, but none of that has happened. I'm just talking about pure old age. I've taken mine out and have given it a good cleaning when servicing the starter clutch, and it sure pulled on the case real strong on reassembly but I didn't have a gaussmeter to check the flux. My feeling is magnetic deterioration is not very likely as lots older bikes are still running fine. I think I have boiled down my problem to a bad connection or other wiring harness issue, but I just need confidence about my rotor's strength to proceed.